1. Field of the Invention
The present invention relates to a surface scan measuring instrument, a surface scan measuring method, a surface scan measuring program and a recording medium storing the program. More specifically, for instance, it relates to a surface scan measuring instrument or the like that scans a surface of a workpiece for measuring a surface roughness, a waviness and a contour of the workpiece.
2. Description of Related Art
Conventionally, a roughness measuring machine, a contour measuring machine, a roundness measuring machine, a coordinate measuring machine and the like have been know as a measuring machine that scans a surface of a workpiece with a scanning probe for measuring a surface texture and a three dimensional profile of the workpiece (see a reference: Japanese Patent Laid-Open Publication No. 2000-74661, for instance).
FIG. 11 shows a measuring system 100 using a coordinate measuring machine 1. The measuring system 100 includes a coordinate measuring machine 1 for moving a scanning probe 2, a manually-operated joystick 32, a motion controller 4 for controlling a motion of the coordinate measuring machine 1, and a host computer 5 for operating the coordinate measuring machine 1 thorough the motion controller 4 and for processing a measurement data obtained by the coordinate measuring machine 1 to find a dimension and a form etc. of a workpiece W. In a scan measurement, since a measurement condition should be set, a surface profile data is input as the measurement condition. The surface profile data may be a design data used for designing the workpiece, a measurement data of obtained by measuring a master workpiece and the like. In addition, a scan route, a scan movement speed, a reference retraction of the probe and a sampling pitch are set. As the scan route to be set may be, for instance, a route for a scan measurement of a contour of the workpiece W on a particular cross section with a certain Z-axis coordinate.
To start the measurement, firstly, the scanning probe 2 is moved to a measurement start point. For moving the scanning probe 2 to the measurement start point, coordinates of the measurement start point may be input, or the joystick 32 may be operated. Then, the motion controller 4 outputs a command signal to the coordinate measuring machine 1 to command a movement of the scanning probe 2, so that the scanning probe 2 scans the workpiece surface. In other words, according to the input surface profile data, a command of a scan direction to have the scanning probe 2 move and scan on the workpiece surface while keeping a certain retraction is given to the coordinate measuring machine 1. Then the scanning probe 2 moves toward the commanded scan direction at the set scan speed. During this process, a measurement data is obtained at a predetermined sampling pitch, so that the workpiece W is measured by scanning.
In the scan measurement, the surface profile data of the workpiece and the scan route should be set in advance of the measurement. When, for example, a measurement with a scan route is followed by another measurement with a different scan route, the scan route should be newly set and input. This takes a good deal of time and efforts, and lowers the measurement efficiency. Also, since the setting is a time-consuming work, operators might feel that the measurement is troublesome.
If the movement of the scanning probe 2 can be controlled using the joystick 32, it will be convenient because the operators can freely select the scan route and the scan speed depending on the condition to operate the scanning probe 2. However, since the scanning probe 2 includes a high-sensitivity sensor that detects a slight displacement caused when abutting on the workpiece W, the scanning probe 2 might be damaged if the scanning probe 2 abuts on the workpiece W with a force greater than an allowable value. For instance, an accuracy around 0.5 mm is required as the allowable value of a probe retraction. With this configuration, it is impossible to manually operate the scanning probe 2 while keeping the scanning probe 2 in contact with the workpiece W.